Polyaxial bone anchor with pop-on shank, shank, friction fit retainer, winged insert and low profile edge lock

Abstract

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A down-loadable compression insert, a down-loadable friction fit split retaining ring having inner and outer tangs and an up-loadable shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61 / 627,374 filed Oct. 11, 2011 that is incorporated by reference herein.[0002]This application is also a continuation-in-part of U.S. patent application Ser. No. 13 / 573,516 filed Sep. 19, 2012 that claims the benefit of U.S. Provisional Patent Application Ser. No. 61 / 626,250 filed Sep. 23, 2011, both of which are incorporated by reference herein. This application is also a continuation-in-part of U.S. patent application Ser. No. 13 / 573,303 filed Sep. 7, 2012 that claims the benefit of U.S. Provisional Patent Application Ser. No. 61 / 573,508 filed Sep. 7, 2011, both of which are incorporated by reference herein. This application is also a continuation-in-part of U.S. patent application Ser. No. 13 / 506,365 filed Apr. 13, 2012 that claims the benefit of U.S. Provisional Patent Application Ser. No. 61 / 517,088 filed Apr. 13, 2011, both of which are incorporated ...

AI Technical Summary

Benefits of technology

The invention is a polyaxial bone screw assembly that includes a shank, a receiver, a compression insert, and a friction fit expansion locking split retainer. The retainer is designed to securely hold the shank head in place and resist larger pull out forces on the assembly. The assembly is stronger and more secure compared to previous designs that use some type of contractile locking engagement between parts. The retainer can be expanded and locked in place, allowing for adjustment or removal of the rod or other connecting member without loss of the desired angular relationship between the shank and the receiver. The technical effects of this invention include improved stability and secure fixation of the bone screw assembly to the bone, as well as improved adjustability and ease of removal of the connecting member.

Problems solved by technology

Collect-like structures extending downwardly from lower pressure inserts, when used in modular polyaxial screw designs, as shown in the prior art, have been found to be somewhat weak with respect to pull-out forces encountered during some spinal reduction procedures.

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